The H2OhNo! is a water sensor alarm kit that you build yourself. When water is detected across the sense pins an alarm goes off and an LED starts blinking. If you’ve ever had a water heater explode or tried to create submersible electronics you know how important it is to be able to detect when water is around!

Underneath the default function of H2OhNo! is a small but powerful development board for the ATtiny85 microcontroller. The board includes a buzzer, LED, a coin cell battery, and the ability to detect analog and digital sensors. This mixture of parts creates a great low-cost tool to learn how to program and sense things!

This board can be re-programmed to be an Annoy-A-Tron (originally made by Think Geek). Please annoy respectfully, otherwise your board may get demolished.